The goals of this proposal are to identify hormonal and genetic factors which are associated with the development of polycystic ovary syndrome (PCOS). The typical features of PCOS become conspicuous during the peri-pubertal period. There are three major goals of this study. The first is to determine the natural history of premature pubarche. The second is to determine the ontogeny of the increased LH/FSH ratio in PCOS. And, the third is to identify genetic markers associated with an increased risk to develop PCOS.